402 DR PETTIGREW ON THE PHYSIOLOGY OF WINGS. 



the wing. It is the posterior or thin flexible margin of the wing which is more 

 especially engaged in producing the sound, and if this be removed, or if this 

 portion of the wing, as is the case in the bat and owl, be constructed of very 

 soft materials, the character of the note is altered. An artificial wing, if pro- 

 perly constructed and impelled at a sufficiently high speed, emits a drumming 

 noise, which closely resembles the note produced by the vibration of short- 

 winged, heavy-bodied birds, all which goes to prove that sound is a concomitant 

 of rapidly vibrating wings. 



ARTIFICIAL FLIGHT. 



The subject of artificial flight, notwithstanding the large share of attention 

 bestowed upon it, has been particularly barren of results. This is the more to 

 be regretted, as the interest which has been taken in it from early Greek and 

 Roman times has been universal. The unsatisfactory state of the question is 

 to be traced to a variety of causes, the most prominent of which are — 



1st, The extreme difficulty of the problem. 



2d, The incapacity or theoretical tendencies of those who have devoted 

 themselves to its elucidation. 



3d, The great rapidity with which wings, especially insect wings, vibrate, 

 and the difficulty experienced in analysing their movements. 



4th, The great weight of all flying things when compared with a correspond- 

 ing volume of air. 



5th, The discovery of the balloon, which has retarded the science of aerosta- 

 tion, by misleading men's minds and causing them to look for a solution of the 

 problem by the aid of a machine lighter than the air, and which has no analogue 

 in nature. Flight has been unusually unfortunate in its votaries. It has been 

 cultivated by profound thinkers, especially mathematicians, who have worked 

 out innumerable theorems, but who, it would appear, never bethought them of 

 verifying their results by experiment ; and by uneducated charlatans who, 

 despising the abstractions of science, have made the most ridiculous attempts 

 at a practical solution of the problem. Thus bandied about, artificial flight has 

 become the idol of a few and the jest of the many. The term has been employed, 

 on the one hand, to represent the highest soarings of the human mind, and on 

 the other, to typify the extinction or aberration of intellect, the word flighty 

 signifying whatever is Utopian or foolish. 



Flight, as the question stands at present, may be divided into two principal 

 varieties which represent two great sects or schools — 



1st, The Balloonists, or those who advocate the employment of a machine 

 specifically lighter than the air. 



2d, Those who believe that weight is necessary to flight. 



The second school may be subdivided into (a) those who advocate the 



